CSF blocks bandwidth benchmarking

Hello all,
I have stumbled upon a roadblock and requesting for help!

I am working with the following:
-Data center: Tokyo
-OS: Ubuntu 20.04 LTS
-Firewall: CSF (https://configserver.com/cp/csf.html)
-Bandwidth benchmarking tool: SpeedTest (https://github.com/taganaka/SpeedTest)

Issue:
**SpeedTest produces expected result when CSF is disabled.

However, when CSF is enabled, it fails to produce any result and outputs like the following:
---from here-------------------------------
Server: Bunkyo speed.coe.ad.jp:8080 by IPA CyberLab (2.25277 km from you): 2147483647 ms
Ping: 2147483647 ms.
Jitter: Jitter measurement is unavailable at this time.
Determine line type (2) **
Very-slow-line line type detected: profile selected slowband

Testing download speed (2) **
Download: 0.00 Mbit/s
Testing upload speed (2) **
Upload: 0.00 Mbit/s
---to here---------------------------
As you can see, it takes an unexpected amount of time to ping a server just 2.2 km away!
Also Jitter measurement becomes unavailable for some reason.
I have opened all usual ports on the firewall.

Have anyone else experienced such issues with CSF?
Is there a port I may open to avoid this issue?
Any suggestion will help.

Best regards,
A.R